Image pickup apparatus and control method

ABSTRACT

An image pickup apparatus includes a shake detecting unit configured to detect a shake of the image pickup apparatus; a first and a second optical correcting unit configured to move in a direction different from an optical axis so as to correct optically an image shake; a first position detecting unit configured to detect a position of the first optical correcting unit and output a first position detection signal; a second position detecting unit configured to detect a position of the second optical correcting unit and output a second position detection signal; and a controlling unit configured to control the first optical correcting unit and the second optical correcting unit. A range for detecting a position of the first position detecting unit is different from that of the second position detecting unit.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to an image pickup apparatus and a control methodtherefor.

2. Description of the Related Art

A shake (image shake) of an object image can be caused by the shaking ofa user's hand which holds a camera main body (causing a hand shaking)when capturing an image by an image pickup apparatus such as a digitalcamera. There has been proposed an image pickup apparatus comprising animage shake correcting unit for correcting the image shake.

Optical image shake correction processing and electronic image shakecorrection processing have been used as conventional correctionprocessing by the image shake correcting unit. The optical image shakecorrection processing detects vibration applied to a camera main bodywith an angular velocity sensor or the like. An image shake correctinglens provided in an imaging optical system is moved depending on theresult of the detection. Thereby, the image focused in a light-receivingplane of an imaging element is moved to correct the image shake byaltering the direction of an optical axis in the imaging optical system.Also, the electronic image shake correction processing is processing forartificially correcting the image shake by performing an imageprocessing on a captured image.

The performance of the image shake correction according to theconventional image shake correcting unit is likely to affect somedifference, for example, the difference depending on a photographingconditions, characteristics of a photographer's hand shaking, or thelike. The difference depending on the characteristics of thephotographer's hand shaking may be a difference of frequency band due tothe specific photographer's large hand shaking. Also, the differencedepending on the photographing conditions is considered to beconditions, for example, when photographing while riding and whenphotographing while walking or the like. Such conditions, a shake amountcapable of correcting the image shake by an image shake correcting unitis required to be larger because an image shake amount is large.However, the size of the image shake correcting unit may be increased toincrease the image shake correction amount.

Japanese Patent Laid-Open No. 2009-258389 discloses an image shakecorrecting device comprising a first movable barrel for holding a firstcorrection member and a second movable barrel for holding a secondcorrection member, and a fixing member between the first movable barreland the second movable barrel.

Japanese Patent Laid-Open No. 2009-258389 discloses an image shakecorrecting device for driving the first correction member and the secondcorrection member inversely to obtain a large correction angle with fewdrive stroke. However, the performance of the image shake correction isreduced depending on the differences between the characteristics of thephotographer's hand shaking, the photographing conditions or the likewhen the correction angle is only expanded, such as the image shakecorrecting device.

SUMMARY OF THE INVENTION

The present invention provides an image pickup apparatus for preventinga reduction in performance of image shake correction due to differencesdepending on the characteristics of a photographer's hand shaking orphotographing conditions.

According to the present embodiment, an image pickup apparatus isprovided that includes a shake detecting unit configured to detect ashake of the image pickup apparatus; a first optical correcting unit anda second optical correcting unit configured to move in a directiondifferent from an optical axis so as to correct optically an imageshake; a first position detecting unit configured to detect a positionof the first optical correcting unit and output a first positiondetection signal; a second position detecting unit configured to detecta position of the second optical correcting unit and output a secondposition detection signal; and a controlling unit configured to controlthe first optical correcting unit based on a shake signal output fromthe shake detecting unit and the first position detection signal, andcontrol the second optical correcting unit based on the shake signaloutput from the shake detecting unit and the second position detectionsignal, wherein a range for detecting a position of the first positiondetecting unit is different from that of the second position detectingunit.

According to the present invention, an image pickup apparatus can beprovided that is not susceptible to the influence of a reduction inperformance of the image shake correction due to differences dependingon a photographing conditions, a shake amount, or a shake frequency bythe user and the like to realize a better image shake correction.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments (with reference to theattached drawings).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating an exemplary configuration of an imagepickup apparatus according to the present embodiment.

FIG. 2 is a diagram illustrating a configuration of an image shakecorrecting device according to the present embodiment.

FIG. 3 is an exploded perspective view of an image shake correcting lensdrive unit.

FIG. 4 is a diagram illustrating a configuration of an image shakecorrecting lens drive unit.

FIG. 5 is a diagram illustrating a mechanism for correcting a shakesignal.

FIG. 6 is a flow chart illustrating processing for calculating a targetposition of an image shake correcting lens.

FIG. 7 is a block diagram of a configuration inside of an image shakecorrecting control unit and a lens control unit according to a secondembodiment of the present invention.

FIG. 8 is a flow chart illustrating processing for detecting a targetposition of an image shake correcting lens according to a secondembodiment of the present invention.

FIGS. 9A and 9B are tables illustrating a control condition of a firstand a second image shake correcting lenses.

FIGS. 10 A and 10B are diagrams illustrating a relationship of adetection accuracy for a current position detecting unit.

DESCRIPTION OF THE EMBODIMENTS First Embodiment

FIG. 1 is a diagram illustrating an exemplary configuration of an imagepickup apparatus according to the present embodiment. The image pickupapparatus as shown in FIG. 1 is a digital still camera. Also, the imagepickup apparatus according to the present embodiment may have a functionof moving image photographing.

The image pickup apparatus as shown in FIG. 1 comprises a zoom unit 101to a control unit 119. The zoom unit 101 is a portion of a photographinglens with variable magnification that constitutes an image formingoptical system. The zoom unit 101 comprises a zoom lens for altering themagnification of the photographing lens. A zoom drive unit 102 controlsa drive of the zoom unit 101 according to the control of the controlunit 119. A first image shake correcting lens 103 is a correction memberfor correcting an image shake. The first image shake correcting lens 103is configured to be movable in a direction perpendicular to an opticalaxis of a photographing lens. An image shake correcting lens drive unit104 controls the drive of the first image shake correcting lens 103. Asecond image shake correcting lens 113 has a configuration similar tothat of the first image shake correcting lens 103. Also, the secondimage shake correcting lens 113 is drive-controlled by the image shakecorrecting lens drive unit 104.

An aperture-shutter unit 105 is a mechanical shutter with an aperturefunction. An aperture-shutter drive unit 106 drives the aperture-shutterunit 105 according to a control of a control unit 119. A focus lens 107is a portion of the photographing lenses and is configured to enablealtering the position of the focus lens 107 according to the opticalaxis of the photographing lens. A focus drive unit 108 drives the focuslens 107 according to the control of the control unit 119.

An image unit 109 converts an optical image by the photographing lensinto an electric signal in pixel units by using an imaging element suchas a CCD image sensor and a CMOS image sensor. The “CCD” stands for“Charge Coupled Device”. The “CMOS” stands for “ComplementaryMetal-Oxide”. An imaging signal processing unit 110 performs A/Dconversion, correlating double sampling, gamma correction, white balancecorrection, color interpolation processing and the like to convert theelectric signal output from the image unit 109 into a video signal. Avideo signal processing unit 111 processes the video signal output fromthe imaging signal processing unit 110 depending on the use. Morespecifically, the video signal processing unit 111 generates a video fordisplay and performs an encoding process and a data filing for recordingor the like.

A display unit 112 displays the image as necessary based on the videosignal for display which the video signal processing unit 111 outputs. Apower source unit 115 supplies the power source to the whole imagepickup apparatus depending on the use. An external input and outputterminal unit 116 inputs and outputs a communication signal and thevideo signal between the external input and output terminal unit 116 andan external device. An operation unit 117 comprises a button, a switchor the like to provide an instruction to the image pickup apparatus bythe user. A store unit 118 stores a variety of data such as videoinformation. For example, the control unit 119 comprising for example, aCPU, a ROM, and a RAM, deploys the control program stored in the ROM tothe RAM to carry out the instruction in the CPU to control each unit ofthe image pickup apparatus and obtain operation of the image pickupapparatus including a variety of operations as described below. The“CPU” stands for “Central Processing Unit”. The “ROM” stands for “ReadOnly Memory”. The “RAM” stands for “Random Access Memory”.

The operation unit 117 comprises a release button configured to turn“ON” a first switch (SW1) and a second switch (SW2) in turn depending ona pressing amount. The release switch SW1 turns “ON” when the releasebutton is half-pressed, and the release switch sw2 turns “ON” when therelease button is fully-pressed. When the release switch SW1 turns “ON”,the control unit 119 calculates an AE evaluation value based on thevideo signal for a display which the video signal processing unit 111outputs to the display unit 112. Then, the control unit 119 controls thefocus drive unit 108 based on the AE evaluation value to detect thefocus automatically.

In addition, the control unit 119 performs AE processing to determine anaperture value and a shutter speed to obtain an appropriate exposureamount based on the information about brightness of the video signal anda predetermined program diagram. When the release switch SW2 is turned“ON”, the control unit 119 performs photographing at the determinedaperture value and the shutter speed, and controls each of theprocessing units to store the image data obtained from the image unit109 to the store unit 118.

The operation unit 117 further comprises an image shake correctingswitch capable of selecting a shake correction mode. When the shakecorrection mode is selected by the image shake correcting switch, thecontrol unit 119 instructs the image shake correcting lens drive unit104 to perform the image shake correcting operation until theinstruction of “image shake correcting-off” is issued. Also, theoperation unit 117 comprises a photographing-mode select switch capableof selecting either a still image photographing mode or a moving imagephotographing mode. The control unit 119 can alter the operationcondition of the image shake correcting lens drive unit 104 according tothe selection of the photographing mode by the operation of thephotographing-mode select switch. The image shake correcting deviceaccording to the present embodiment is composed of the image shakecorrecting lens drive unit 104.

Also, the operation unit 117 comprises a play mode select switch forselecting a play-mode. When the play mode is selected by operating theplay mode select switch, the control unit 119 stops the operation forthe image shake correction. Also, the operation unit 117 comprises amagnification change switch for performing the instruction for thechange of the zoom magnification. When the instruction for the change ofthe zoom magnification is performed by operating the magnificationchange switch, the zoom drive unit 102 that has received the instructionvia the control unit 119 drives the zoom unit 101 to move the zoom unit101 to the instructed zoom position.

FIG. 2 is a diagram illustrating a configuration of the image shakecorrecting device according to the present embodiment. A first vibrationsensor 201 is, for example, an angular velocity sensor, and detectsvibration in a direction perpendicular to the image pickup apparatus(pitch direction) in a natural attitude (an attitude in which thedirection of the image closely fits the horizontal direction). A secondvibration sensor 202 is, for example, an angular velocity sensor, anddetects vibration in a direction parallel to the image pickup apparatusin the natural attitude (yaw direction). A first image shake correctingcontrol unit 203 outputs a correction position control signal of theimage shake correcting lens in the pitch direction to control a drive ofthe image shake correcting lens. A second image shake correcting controlunit 204 outputs the correction position control signal of the imageshake correcting lens in the yaw direction to control the drive of theimage shake correcting lens.

A first lens position control unit 205 performs feedback control fromthe correction position control signal in the pitch direction from thefirst image shake correcting control unit 203 and the positioninformation of the image shake correcting lens in the pitch directionfrom a first Hall element 209. Thereby the first lens position controlunit 205 drives, for example, a first driving unit 207 that is anactuator. Also, a second lens position control unit 206 performs thefeedback control from the correction position control signal in the yawdirection from the second image shake correcting control unit 204 andthe position information of the image shake correcting lens in the yawdirection from a second Hall element 210. Thereby, the second lensposition control unit 206 drives, for example, a second driving unit 208that is the actuator.

Next, a description will be given of drive control operation of thefirst image shake correcting lens 103 by the image shake correcting lensdrive unit 104. A shake signal (angular velocity signal) representing ashake in the pitch direction of the image pickup apparatus is suppliedfrom the first vibration sensor 201 to the first image shake correctingcontrol unit 203. Also, the shake signal (angular velocity signal)representing the shake in the yaw direction of the image pickupapparatus is supplied from the second vibration sensor 202 to the secondimage shake correcting control unit 204.

The first image shake correcting control unit 203 generates thecorrection position control signal for driving the first image shakecorrecting lens 103 in the pitch direction based on the supplied shakesignal and outputs the correction position control signal to the firstlens position control unit 205. Also, the second image shake correctingcontrol unit 204 generates the correction position control signal fordriving the first image shake correcting lens 103 in the yaw directionbased on the supplied shake signal and outputs the correction positioncontrol signal to the second lens position control unit 206.

The first Hall element 209 outputs the signal having a voltage dependingon magnetic field strength by a magnet disposed in the first image shakecorrecting lens 103 as the position information of the first image shakecorrecting lens 103 in the pitch direction. The second Hall element 210outputs the signal having a voltage depending on magnetic field strengthby the magnet disposed in the first image shake correcting lens 103 asthe position information of the first image shake correcting lens 103 inthe yaw direction. The position information is supplied to the firstlens position control unit 205 and the second lens position control unit206.

The first lens position control unit 205 controls the feedback whiledriving the first driving unit 207 so that the signal value from thefirst Hall element 209 converges to a correction position control signalvalue from the first image shake correcting control unit 203. Also, thesecond lens position control unit 206 controls the feedback whiledriving the second driving unit 208 so that the signal value from thesecond Hall element 210 converges to the correction position controlsignal value from the second image shake correcting control unit 204.

Note that the output of the first Hall element 209 and the second Hallelement 210 is adjusted so that the first image shake correcting lens103 is moved to the predetermined position with respect to thepredetermined correction position control signal because the positionsignal value output from the first Hall element 209 and the second Hallelement 210 are variable.

The first image shake correcting control unit 203 outputs the correctionposition control signal for moving the position of the first image shakecorrecting lens 103 to cancel the image shake of the object image basedon the shake information from the first vibration sensor 201. The secondimage shake correcting control unit 204 outputs the correction positioncontrol signal for moving the position of the first image shakecorrecting lens 103 to cancel the image shake based on the shakeinformation from the second vibration sensor 202.

For example, the first image shake correcting control unit 203 and thesecond image shake correcting control unit 204 generate a correctionspeed control signal or a correction position control signal byperforming filter processing or the like on the shake information (anglevelocity signal) or the shake information. By the above operation, ifthere is vibration such as a hand shaking at the image pickup apparatuswhen photographing, the image shake can be prevented to a certain levelof vibration. Also, the first image shake correcting control unit 203and the second image shake correcting control unit 204 detect a panningstate of the image pickup apparatus based on the shake information fromthe first vibration sensor 201 and the second vibration sensor 202, andthe output of the first Hall element 209 and the second Hall element toperform a panning control.

The drive control of the second image shake correcting lens 113 by theimage shake correcting lens drive unit 104 is similar to that of thefirst image shake correcting lens 103 by the image shake correcting lensdrive unit 104. In other words, the first image shake correcting controlunit 203 generates the correction position control signal for drivingthe second image shake correcting lens 113 in the pitch direction basedon the supplied shake signal and outputs the position correction controlsignal to a third lens position control unit 211. Also, the second imageshake correcting control unit 204 generates the correction positioncontrol signal for driving the second image shake correcting lens 113 inthe yaw direction based on the supplied shake signal and outputs thecorrection position correction control signal to a fourth lens positioncontrol unit 212.

The third lens position control unit 211 controls feedback while drivinga third driving unit 214 so that a signal value from a third Hallelement 216 converges to the correction position control signal valuefrom the first image shake correcting control unit 203. Also, the fourthlens position control unit 212 controls the feedback while driving afourth driving unit 215 so that the signal value from a fourth Hallelement 213 converges to the correction position control signal valuefrom the second image shake correcting control unit 204.

In the present embodiment, the first image shake correcting control unit203, the first lens position control unit 205, and the first drivingunit 207 correct the low-frequency components of the shake signal in thepitch direction. Also, the first image shake correcting control unit203, the third lens position control unit 211 and the third driving unit214 correct the high-frequency components of the shake signal in thepitch direction.

Also, the second image shake correcting control unit 204, the secondlens position control unit 206 and the second driving unit 208 correctthe low-frequency components of the shake signal in the yaw direction.Also, the second image shake correcting control unit 204, the fourthlens position control unit 212, and the fourth driving unit 215 correctthe high-frequency components of the shake signal in the yaw direction.

FIG. 3 is an exploded perspective view of an image shake correcting lensdrive unit 104. The image shake correcting lens drive unit 104 comprisesthe first image shake correcting lens 103, a movable barrel 122, a fixedbase plate 123, a rolling ball 124, a first electromagnetic drive unit207, and a second electromagnetic drive unit 208. Also, the image shakecorrecting lens drive unit 104 comprises an urging spring 127, a firstposition sensor 209, a second position sensor 210, and a sensor holder129.

The first electromagnetic drive unit 207 comprises a first magnet 1251,a first coil 1252, and a first yoke 1253. The second electromagneticdrive unit 208 comprises a second magnet 1261, a second coil 1262, and asecond yoke 1263.

The first image shake correcting lens 103 is a first correcting opticalmember capable of offsetting an optical axis. The first image shakecorrecting lens 103 is drive controlled by the first image shakecorrecting control unit 203 and the second image shake correctingcontrol unit 204. Thereby, an image shake correction operation formoving an optical image for passing through the image optical system isperformed to ensure stability of the image on an imaging plane. Notethat while a correcting lens is used as a correction optical systemaccording to the present embodiment, an imaging unit such as the CCD toa photographing optical system may be driven to ensure the stability ofthe image on the imaging plane. In other words, the imaging unit may beused as a unit for correcting the image shake.

The movable barrel 122 is a first movable portion for holding the firstimage shake correcting lens 103 at the central opening. The movablebarrel 122 holds the first magnet 1251 and the second magnet 1252. Also,the movable barrel 122 comprises three rolling ball receivers and issupported so as to be capable of moving in the plane perpendicular tothe optical axis by the rolling ball 124. Also, the movable barrel 122comprises three spring hooks, which are capable of holding one end ofthe urging spring 127.

The fixed base plate 123 is a first fixing member formed into a cylindershape. The fixed base plate 123 comprises three followers 1231 on theouter circumference unit. The movable barrel 122 is arranged at thecentral opening of the fixed base plate 123. Thereby, the movable amountof the movable barrel 122 can be limited.

Also, the fixed base plate 123 holds the first coil 1252 and the firstyoke 1253 at the point where the fixed base plate 123 faces themagnetized surface of the first magnet 1251. Also, the fixed base plate123 holds the second coil 1262 and the second magnet yoke 1263 at thepoint where the fixed base plate 123 faces the magnetized surface of thesecond magnet 1261. Also, the fixed base plate 123 comprises threerolling ball receivers and holds movably the movable barrel 122 in theplane perpendicular to the optical axis through the rolling ball 124. Inaddition, the fixed base plate 123 comprises three spring hooks, whichhold one end of the urging spring 127.

In this example, the first electromagnetic drive unit 207 is thewell-known voice coil motor. An electric current is passed through thefirst coil 1252 attached to the fixed base plate 123 to generate theLorentz force between the first magnet 1251 fixed to the movable barreland the fixed base plate 123 to drive the movable barrel 122. The secondelectromagnetic drive unit 208 is arranged similarly to the voice coilmotor of the first electromagnetic drive unit 207 rotated by 90 degreesand thus, a detailed description thereof will be omitted.

The urging spring 127 is a tensile spring that generates an urging forceproportional to the deformed amount. One end of the urging spring 127 isfixed to the movable barrel 122 and the other end that is fixed to thefixed base plate 123 to generate the urging force therebetween. Therolling ball 124 is held by this urging force to keep the contact statewith the fixed base plate 123 and the movable barrel 122.

The position sensor 209 and the position sensor 210 are two magneticsensors with a Hall element that reads the magnetic flux of the firstmagnet 1251 and the second magnet 1261. The movement in the plane of themovable barrel 122 can be detected from the change of the output.

The sensor holder 129 is configured in a substantial disk-shaped andfixed to the fixed base plate 123. The two position sensors 209 and 210can be held at the position where the position sensors face the firstmagnet 1251 and the second magnet 1261. Also, the sensor holder 129 canhouse the movable barrel 122 inside the space formed together with thefixed base plate 123. Thereby, the inside units can be prevented fromfalling away even when an impact force is applied to the image shakecorrecting device or the difference of the attitude is varied. The imageshake correcting lens drive unit 104 can allow the first image shakecorrecting lens 103 to move to any position in the plane perpendicularto the optical axis according to the configuration described above.

FIG. 4 is a diagram a positional relationship of the image shakecorrecting lens drive unit comprising the first image shake correctinglens 103 and the second image shake correcting lens 113 respectively. Apart of the image shake correcting lens drive unit is exploded oromitted for the same of explanation in FIG. 4. The movable barrel 132 isa second movable unit in the image shake correcting lens drive unit 104for holding the second image shake correcting lens 113 at the centralopening. The fixed base plate 133 is a second fixing member in the imageshake correcting lens drive unit 104 with the second image shakecorrecting lens 113. The image shake correcting lens drive unit 104 withthe second image shake correcting lens 113 has a configuration similarto that of the image shake correcting lens drive unit 104 with the firstimage shake correcting lens 103, except for the shape of the lens andthe movable barrel 132 holding the lens, and thus, a detaileddescription thereof will be omitted.

FIG. 5 is a diagram a mechanism for correcting a shake signal in a pitchdirection in the image shake correcting device according to the presentembodiment. A mechanism for correcting the shake signal in the yawdirection is realized by the second image shake correcting control unit204, the second lens position control unit 206, the fourth lens positioncontrol unit 212, the second driving unit 208 and the fourth drivingunit 215 being similar to that shown in FIG. 4, and thus, a descriptionthereof will be omitted.

In FIG. 5, the first vibration sensor 201 detects a shake informationsignal (angle velocity signal) applied to the image pickup apparatus.The first image shake correcting control unit 203 comprises a LPF (lowpass filter) 503, a panning determination unit 502, and a first drivelimit 505. The image shake signal detected by the first vibration sensor201 is integrated by the LPF 503 with which the time constant until thefilter becomes stable is variable to generate a shake angle signal fromwhich only the low-frequency components are extracted. The phrase “Atime constant until the filter becomes stable is variable” means, forexample, that the coefficient of the filter is varied to allow a cut-offfrequency to be variable, or that the buffer for holding the result ofthe calculation (median) in the filter calculation can be rewrittenfreely at any timing.

The panning determination unit 502 determines the panning operation ofthe image pickup apparatus to perform time constant change processinguntil the filter of the LPF 503 becomes stable. More specifically, thepanning determination unit 502 determines that the panning operation isdone if the shake signal detected by the first vibration sensor 201 isover a predetermined value. The panning determination unit 502 maydetermine that the panning operation is done if the current positions ofthe first image shake correcting lens 103 and the second image shakecorrecting lens 113 are over the predetermined value. Also, the panningdetermination unit 502 may determine that the panning operation is done,if the target positions of the first image shake correcting lens 103 andthe second image shake correcting lens 113 are over the predeterminedvalue. Thereby, the first image shake correcting lens 103 and the secondimage shake correcting lens 113 can be prevented from being driven abovethe movable range and the photographing image can be prevented frombeing unstable due to a swing-back immediately after the panningoperation if a large shake is applied to the image pickup apparatus.

The target position of the first image shake correcting lens generatedfrom the low-frequency components of a hand shake angle signal generatedabove is input to the first lens position control unit 205 after a driveamount is limited in a first drive limit 505. Also, the signal forsubtracting the position information of the first image shake correctinglens 103 amplified by a first position detecting signal amplifier 507from the target position of the first image shake correcting lens isheld as the target position of the second image shake correcting lens113.

The position information of the first image shake correcting lens 103that has been detected by the first Hall element 209 is compared to thelens target position output from the first drive limit 505 after theamplification to the predetermined amplitude by the first positiondetecting signal amplifier 507. Then, the image shake correctingoperation is carried out by the position feedback control through thefirst driving unit 207.

Also, the position information of the second image shake correcting lens113 that has been detected by the third Hall element 216 is compared tothe target position of the second image shake correcting lens after theamplification to the predetermined amplitude by a third positiondetecting signal amplifier 508. Then, the image shake correctingoperation is carried out by the position feedback control through thethird driving unit 214.

As described above, the result of subtracting the position informationof the first image shake correcting lens 103 amplified by a firstposition detecting signal amplifier 507 from the target position of thefirst image shake correcting lens denotes a remainder of the image shakecorrection by the first image shake correcting lens. The target positionof the second image shake correcting lens 113 is determined in order toremove the remainder of this image shake correction by the drive of thesecond image shake correcting lens. The reason why the remainder occursin the first image shake correcting lens is considered to affect thedrive characteristics (friction influence and influences of the externaldisturbances such as the attitude) of the first image shake correctinglens, the responsiveness and a control band of the first lens positioncontrol unit and the like.

In the first lens position control unit 205 and the third lens positioncontrol unit 211, any control calculators may be used. In the example, aPID controller is used as the first lens position control unit 205 andthe third lens position control unit 211.

FIG. 6 is a flow chart illustrating of processing for calculating atarget position of an image shake correcting lens according to thepresent embodiment. Firstly, when the processing is started (step S101),the first vibration sensor obtains an image shake signal (step S102).

Next, the panning determination unit 502 determines whether the imagepickup apparatus is at the panning operation (panning) or not (stepS105). If the image pickup apparatus is determined to be panning, itallows the time constant until the LPF 503 becomes stable to be short(step S201). If the image pickup apparatus is not determined to bepanning, the processing for altering the time constant is not performed,and the processing goes to a step S108.

In step S108, the LPF 503 integrates the obtained output value totransform it from angle velocity information to angle information (stepS108). Then, the first drive limit 505 limits the output value of theLPF 503 to the predetermined amplitude (step S109).

Then, in step S109, the output value of the LPF 503 is limited to thepredetermined amplitude by the first drive limit 505 to be input to thefirst lens position control unit 205 (step S116). Thereby, the firstimage shake correcting lens is driven.

Next, the current position of the first image shake correcting lens 103is obtained from a first position detecting amplifier 507 (step S117).Then, the current position obtained in step S117 is subtracted from thetarget position of the first image shake correcting lens calculated instep S109 and stored as the target position of the second image shakecorrecting lens (step S118).

Next, the target position of the second lens stored in the step S118 isinput to the third lens position control unit 211 (step S119) to drivethe second image shake correcting lens. Thereby, the first and secondimage shake correcting lenses can be driven according to the image shakesignal applied to the image pickup apparatus to remove the influence ofthe image shake applied to the image pickup apparatus.

Note that, in the present embodiment, the value that subtracts thecurrent position from the target position of the first image shakecorrecting lens is input without changes as the target position of thesecond image shake correcting lens because the relationship of the imageshake correction angle to the drive stroke of the first image shakecorrecting lens is assumed to be same as that of the second image shakecorrecting lens. However, if the correction angle to the drive stroke ofthe first image shake correcting lens is different from that of thesecond image shake correcting lens, the value that subtracts the currentposition from the target position of the first image shake correctinglens is multiplied by a coefficient in consideration of the image shakecorrection angle to the drive stroke of the second image shakecorrecting lens. In this case, the multiplied result must be input tothe third lens position control unit as the target position of thesecond lens.

(Configuration of a Current Position Detecting Unit)

Here, referring to FIGS. 10A and 10B, a description will be given of arelationship between a detection accuracy for a current positiondetecting unit configured to detect the current positions of the firstimage shake correcting unit and the second image shake correcting unitaccording to the present embodiment. FIGS. 10A and 10B illustrate arelationship between a drive stroke of the image shake correcting lensand the output of the Hall element if the well-known Hall element isused as the position detecting unit of the image shake correcting lens.In principle, because the Hall element can obtain an output proportionalto the magnetic flux density, the Hall element outputs a signal havingthe voltage depending on the magnetic field strength by the magnetdisposed in the image shake correcting lens as the position information.

Conventionally, as shown in FIG. 10A, one Hall element is used to detectthe position on one axis in the drive direction of the image shakecorrecting lens. In this case, when the size of the magnet is reduced orthe like, a detection area of the magnetic flux becomes narrow, and thiscauses the position detection area capable of being detected lineally bythe Hall element to the drive stroke to narrow and cause some area to beincapable of detecting the position correctly in the area with a largedrive stroke. Therefore, the correct position of the image shakecorrecting lens cannot be detected in the area with a large shakecorrection angle (the area with large drive stroke), and this may causethe reduction in the performance of the image shake correction.

Next, the method as shown in FIG. 10B provides two Hall elements bymoving the Hall elements in the well-known drive direction. This methodutilizes the fact that the output of the two Hall elements has as anobject and sets the difference between the outputs of the two Hallsignals to be a position detection signal to allow widening the range inwhich the position can be linearly detected with respect to the drivestroke.

However, the two Hall elements are used for one axis in the drivedirection to detect the position. If it is intended to raise thedetection accuracy of the current positions of all of the two axes ofeach drive axis against the two image shake correcting units, the modeof the FIG. 10A needs 4 Hall elements (2 lenses×2 drive axes) and thatof the FIG. 10B needs 8 Hall elements (2 lenses×2 drive axes×2).Accordingly, the increase of the number may cause an increase of thecost.

Thus, in the present embodiment, the drive stroke of the first imageshake correcting lens is set to be large, as described above, to allowthe correction angle to be wide. Thereby, the current position detectingunit of the first image shake correcting lens has a configuration with ahigh position detection accuracy by using the two Hall elements in FIG.10B.

In contrast, the second image shake correcting lens is controlled tocorrect only the remainder of the image shake correction of the firstimage shake correcting lens. Thus, the drive the stroke of the secondimage shake correcting lens is less than that of the first image shakecorrecting lens. Therefore, the current position detecting unit of thesecond image shake correcting lens can have a configuration with lowposition detection accuracy by using the one Hall element in FIG. 10A.

Accordingly, this embodiment needs 6 Hall elements (the first imageshake correcting unit: 2 drive axes×2+the second image shake correctingunit: 2 drive axes×1) to detect the position. As described above, therole of the first image shake correcting lens and the second image shakecorrecting lens can be divided to set the division of the drive stroketo reduce an increase of the cost of the sensor for detecting theposition of the image shake correcting lens.

Also, the second image shake correcting lens can avoid an increase ofthe size of the correcting device because it has a drive stroke lessthan that of the first image shake correcting lens. Also, the mode byusing the two Hall elements is described as the mode with high positiondetection accuracy according to the present embodiment, but anothersensor such as an optical encoder may be used.

Here, a description will be given of the drive condition of a firstimage shake correcting unit and a second image shake correcting unit inan image shake correcting device according to the present embodimentreferring to FIG. 9. In this example, the first image shake correctinglens 103 functions as the first image shake correcting unit. Also, thesecond image shake correcting lens 113 functions as a second image shakecorrecting unit. Note that the first image shake correcting unit is atilt lens and the second image shake correcting unit is a shift lens inthe present embodiment. However, these configurations are not intendedto a limitation and they may be replaced by each other.

(Target Position of the Image Shake Correction)

A method for determining the target position of the image shakecorrection of the first and second image shake correcting units drivesfirstly the first image shake correcting unit to perform the image shakecorrection according to the image shake signal. Then, a remainder of theimage shake correction is calculated by subtracting the current positionfrom the target position of the first image shake correcting unit. Theremainder is set to be a target position of the image shake correctionof the second image shake correcting unit.

(Correction Angle in the Image Shake Correction)

The image shake correction angle of the first image shake correctingunit is set so as to be wider than that of the second image shakecorrecting unit because the remainder of the correction that has notbeen corrected by the first image shake correcting unit is set to be atarget position of the second image shake correcting unit after theremoval of the large image shake components by the first image shakecorrecting unit and generally, the target position of the second imageshake correcting unit is smaller than that of the first image shakecorrecting unit. Thereby, the method for correcting the image shake canbe divided into a correcting unit configured to correct the image shakemainly with the large drive stroke and a correcting unit configured toremove only the remainder of the correction with the small strokesecondarily to allow the mechanical configuration of the second imageshake correcting unit to be smaller than that of the first image shakecorrecting unit.

(Deterioration in Optical Performance Due to the Lens Driving)

Generally, when the drive amount of the image shake correcting unitbecomes larger, the peripheral light amount, the resolution, and theaberration tend to deteriorate. Thereby, the first image shakecorrecting unit is set to a configuration so as not to causedeterioration in the optical performance due to the lens drivingcompared to the second image shake correcting unit because the driveamount for the image shake correction is likely to be large in the firstcorrecting unit.

(Drive Mode of the Image Shake Correcting Lens)

In the drive mode of the image shake correcting lens, the deteriorationin optical performance of the well-known tilt mode to the optical axisis less than that of the shift mode in the plane perpendicular to theoptical axis. Accordingly, the first image shake correcting lens 103 inthe first correcting unit is set to the drive mode in the tiltingdirection, and the second image shake correcting lens 113 in the secondcorrecting unit is set to the shift drive mode.

(Arrangement Position of the Lens)

Generally, when the lens is arranged closer to the side of the objectimage, the lens has the larger image shake correction angle and lessdeterioration in optical performance with respect to the drive amount ofthe image shake correcting unit. Therefore, in the present embodiment,the first image shake correcting lens 103 is moved closer to the objectimage than the second image shake correcting lens 113.

(Amplification Factor of the Position Detection Signal)

A signal output from the Hall element (Hall element signal) is aposition detection signal of the image shake correcting lens. In theamplification factor of the position detecting signal amplifier foramplifying the Hall element signal to the predetermined magnificationfor detecting the position of the image shake correcting unit, theamplification factor of the first image shake correcting unit is set tobe smaller than that of the second image shake correcting unit. Thisallows the large amplification factor for the Hall signal of theposition detecting signal amplifier to improve the resolution fordetecting the position. However, if the electric signal after theamplification is obtained digitally by an AD converter or the like, adynamic range is often not expanded within a limited voltage range. Theamplification factor of the first image shake correcting unit in thedynamic range, which has high probability of driving significantly isset to be small in order to balance the resolution with the dynamicrange. Also, the amplification factor of the second image shakecorrecting unit for correcting only the remainder of the correction bythe first image shake correcting lens that has a small drive stroke, butcauses many small shakes is set to be large to allow the resolution ofthe position detection to be higher. More specifically, the signalamplification factor by the first position detecting signal amplifier507 that is a first signal amplifying unit is reduced rather than thesignal amplification factor by the third position detecting signalamplifier 508 that is a second signal amplifying unit.

(Frequency Band of a Return Control Unit)

In the remainder components of the correction that is not corrected bythe first image shake correcting unit, the components that has the largeamplitude at the low-frequency is mainly removed. Also, a large portionof the remainder components of the correction has generally thehigh-frequency components that cause by the influences of the externaldisturbance. Therefore, frequency band of a return control unit of thesecond image shake correcting unit for correcting the remainingcorrection of the image shake correction of the first image shakecorrecting unit (a second feedback controlling unit) is set to be higherthan that of the first image shake correcting unit (a first feedbackcontrolling unit).

(Image Shake Correction Angle to the Lens Drive Stroke)

The image shake correction angle to the same drive stroke is differentdepending on the type of the image shake correcting lens because of itsoptical characteristics. The first image shake correcting unit uses alens with an image shake correction angle that is obtained to drive thedrive stroke. The angle is larger than that of the second image shakecorrecting unit because the first image shake correcting unit requiresthe lens with larger image shake correction angle than that of thesecond image shake correcting unit.

The establishment described above can provide an image shake correctingdevice for making the size of the mechanical configuration of the firstimage shake correcting unit that requires a large drive stroke that isas small as possible to obtain a significant effect for the shakecorrection without the increase in the size of the apparatus in thepresent embodiment.

Second Embodiment

In the present embodiment, except for the configuration of the imageshake correcting control unit 203, its configuration is the same as thatof the first embodiment comprising the drive condition of the first andthird image shake correcting lenses and the like, and thus, adescription thereof will be omitted. FIG. 7 illustrates a configurationinside of a first image shake correcting control unit 203, a first lensposition control unit 205, and a third lens position control unit 211.Note that a second image shake correcting control unit 204, a secondlens position control unit 206 and a fourth lens position control unit212 has an inside configuration that is the same as those shown in FIG.7 and thus, a description thereof will be omitted.

In FIG. 7, the first vibration sensor 201 detects a shake signal(angular velocity signal) applied to the image pickup apparatus. The lowpass filter (LPF) 501 extracts the low-frequency components from theshake signal detected by the first vibration sensor 201. The shakesignal of the low frequency extracted by the LPF 501 is integrated bythe LPF 503, for which the time constant until the filter becomes stableis variable, to generate a shake angle signal extracting only thelow-frequency components.

Note that the phrase “A time constant until the Filter becomes stable isvariable” means for example, that the coefficient of the filter isvaried to allow the cut off frequency to be variable, or that the bufferfor holding the result of the calculation (median) in the filtercalculation can be rewritten freely at any timing.

If the panning determination unit 502 determines the panning operation,the time constant change processing until the filter of the LPF 503 and504 become stable is performed. The panning determination unit 502determines the panning operation for example, if the shake signaldetected by the each vibration sensor when the image pickup apparatus issignificantly panned, tilted, or shaken, a current position of eachimage shake correcting lens, or the target position of each image shakecorrecting lens is over the predetermined value. Also, the panningdetermination unit 502 determines the panning operation for example, ifthe position of the first image shake correcting lens 103 or the secondimage shake correcting lens 113 is significantly separated from thecenter position of the lens.

This processing can prevent the image shake correcting lens from beingdriven above the movable range if a large shake is applied to the imagepickup apparatus, and prevent the photographing image from beingunstable due to a swing-back immediately after the panning operation.

In contrast, the low-frequency components extracted by the LPF 501 aresubtracted from the shake signal detected by the vibration sensor 201 toextract the high-frequency components from the shake signal. The LPF 504is, for example, a low pass filter for integrating the high-frequencycomponents, and integrates the high-frequency components of the shakesignal to transform it from angle velocity information to angleinformation to generate the shake angle signal extracting only thehigh-frequency components. Note that the coefficients of the LPF 503 andthe LPF 504 can be varied and output an output of the filter at anymagnification.

The shake angle signals of the low frequency and the high frequency asgenerated above is input to the first lens position control unit 205 andthe third lens position control unit 211, respectively. Morespecifically, the target position of the first image shake correctinglens 103 generated from the low-frequency components controls the driveamount by the first drive limit 505 to be input to the first lensposition control unit 205. Alternatively, the target position of thesecond image shake correcting lens 113 generated from the high-frequencycomponents controls the drive amount by the third drive limit 506 to beinput to the third lens position control unit 211.

The position information of the first image shake correcting lens 103detected by the first Hall element 209 is amplified to a predeterminedamplitude by the first position detecting signal amplifier 507. Then itis compared to the lens target position output from the first drivelimit 505 to carry out the operation of the image shake correction bythe position feedback control through the first driving unit 207. Also,the position information of the second image shake correcting lens 113detected by the third Hall element 216 for detecting the position of thesecond image shake correcting lens 113 is amplified to the predeterminedamplitude by the third position detecting signal amplifier 508. Then itis compared to the lens target position output from the third drivelimit 506 to carry out the operation of the image shake correction bythe position feedback control through the third driving limit 214. Notethat the first lens position control unit 205 and the third lensposition control unit 211 have a configuration using, for example, a PIDcontrol, but, any control arithmetic unit may be used.

Referring to FIG. 8, a description will be given of a control method ofthe image shake correcting lens performed by the image pickup apparatuscomposed as mentioned above. FIG. 8 is a flow chart illustratingprocessing for calculating a target position of an image shakecorrecting lens according to the present embodiment. The processing isperformed at a regular interval of the cycle. Firstly, the processing isstarted (step S101) to obtain a hand shaking signal by the firstvibration sensor 201 (step S102). Then the LPF 501 performs thecalculation for dividing the frequency band of the hand shaking signal(step S103) to store the result of the calculation by the LPF 501 as thelow-frequency components of the hand shaking signal to the memory (stepS104).

Next, the panning determination unit 502 determines whether the imagepickup apparatus is at the panning operation (panning) or not (stepS105). If the image pickup apparatus is determined to be panning, itallows the time constant until the LPF 503 and 504 become stable to beshort (step S106). On the other hand, if the image pickup apparatus isnot determined to be panning, the processing for altering the timeconstant is not performed, and the processing goes to a step S107.

In step S107, the LPF 503 obtains the output value of the LPF 501 storedto the memory in the step S104 (step S107). Then, the LPF 503 integratesthe obtained output value and transforms it from the angle velocityinformation to the angle information (step S108). Then the first drivelimit 505 limits the output value of the LPF 503 to the predeterminedamplitude (step S109). Then, the first drive limit 505 inputs the outputvalue of the LPF 503 to the first lens position control unit 205 (stepS110). Thereby, the first image shake correcting lens 103 is driven.

Next, the output value of the LPF 501 stored in the step S104 issubtracted from the hand shaking signal obtained in the step S102 (stepS111) to extract the high-frequency components of the hand shakingsignal. Thereby, the hand shaking signal is divided into thelow-frequency components and the high-frequency components at the cutofffrequency set by LPF 501.

The LPF 504 integrates the high-frequency components of the extractedhand shaking signal to transform it from the angle velocity signal tothe angle signal (step S112). Then, the third drive limit 506 limits theoutput value of the LPF 504 to the predetermined amplitude (step S113)and inputs it to the third lens position control unit 211 (step S114).Thereby, the second image shake correcting lens 113 is driven to stopthe processing (step S115). As described above, the image shakecorrecting lens is driven to the low-frequency signal and thehigh-frequency signal of the hand shaking signal to remove the influenceof the hand shake applied to the image pickup apparatus.

(Configuration of the Current Position Detecting Unit)

The relationship between the position detection accuracy of the currentposition detecting unit for detecting the current position of the firstimage shake correcting lens 103 and the second image shake correctinglens 113 according to this embodiment is similar to that of the firstembodiment and thus, a detailed description thereof will be omitted. Inthe present embodiment, the first image shake correcting lens 103 tendsto have a large drive stroke because it is driven to extract only thelow-frequency components in the hand shaking signal and correct these asdescribed above. Thus, the current position detecting unit of the firstimage shake correcting lens 103 has a configuration with high positiondetection accuracy by using two Hall elements in FIG. 10B to correct thelarge hang shake with high accuracy by setting the correction angle tobe wide.

In contrast, the second image shake correcting lens 113 has a correctionamount less than that of the first image shake correcting lens 103, andcauses the drive stroke to be less because the second image shakecorrecting lens 113 is driven to extract only the high-frequencycomponents in the hand shaking signal and correct these. Therefore, thecurrent position detecting unit of the second image shake correctinglens can have a configuration with low detection accuracy by using oneHall element in FIG. 10A. As described above, the frequency band forcorrecting the hand shaking of the first image shake correcting lens 103and the second image shake correcting lens 113 can be divided to set thedivision of the drive stroke to obtain the effect similar to that of thefirst embodiment.

As described above, the present embodiment can also provide an imageshake correcting device for preventing a reduction in the image shakecorrecting performance due to the differences depending on thecharacteristics of the photographer's hand shaking or the photographingconditions.

OTHER EMBODIMENTS

Embodiments of the present invention can also be realized by a computerof a system or apparatus that reads out and executes computer executableinstructions recorded on a storage medium (e.g., non-transitorycomputer-readable storage medium) to perform the functions of one ormore of the above-described embodiment(s) of the present invention, andby a method performed by the computer of the system or apparatus by, forexample, reading out and executing the computer executable instructionsfrom the storage medium to perform the functions of one or more of theabove-described embodiment(s). The computer may comprise one or more ofa central processing unit (CPU), micro processing unit (MPU), or othercircuitry, and may include a network of separate computers or separatecomputer processors. The computer executable instructions may beprovided to the computer, for example, from a network or the storagemedium. The storage medium may include, for example, one or more of ahard disk, a random-access memory (RAM), a read only memory (ROM), astorage of distributed computing systems, an optical disk (such as acompact disc (CD), digital versatile disc (DVD), or Blu-ray Disc (BD)™),a flash memory device, a memory card, and the like.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

This application claims the benefit of Japanese Patent Application No.2013-244531, filed Nov. 27, 2013, which is hereby incorporated byreference herein in its entirety.

What is claimed is:
 1. An image pickup apparatus comprising: a shakedetecting unit configured to detect a shake of the image pickupapparatus; a first optical correcting unit and a second opticalcorrecting unit configured to move in a direction different from anoptical axis so as to correct optically an image shake; a first positiondetecting unit configured to detect a position of the first opticalcorrecting unit and output a first position detection signal; a secondposition detecting unit configured to detect a position of the secondoptical correcting unit and output a second position detection signal;and a controlling unit configured to control the first opticalcorrecting unit based on a shake signal output from the shake detectingunit and the first position detection signal, and control the secondoptical correcting unit based on the shake signal output from the shakedetecting unit and the second position detection signal, wherein a rangefor detecting a position of the first position detecting unit isdifferent from that of the second position detecting unit.
 2. The imagepickup apparatus according to claim 1, wherein the range for detectingthe position of the first position detecting unit is wider than that ofthe second position detecting unit.
 3. The image pickup apparatusaccording to claim 2, wherein a second shake signal that is a shakesignal for controlling the second optical correcting unit is acorrection signal calculated by subtracting the first position detectionsignal from a first shake signal that is a shake signal for controllingthe first optical correcting unit.
 4. The image pickup apparatusaccording to claim 2, wherein the first shake signal, which is the shakesignal for controlling the first optical correcting unit, is a signal oflow-frequency components extracted from the shake signal output from theshake detecting unit and the second shake signal, which is the shakesignal for controlling the second optical correcting unit, is a signalof high-frequency components extracted from the shake signal output fromthe shake detecting unit.
 5. The image pickup apparatus according toclaim 2, wherein an image shake correction angle of the first opticalcorrecting unit is wider than that of the second optical correctingunit.
 6. The image pickup apparatus according to claim 2, wherein thefirst optical correcting unit is an optical element having adeterioration in optical performance less than that of the secondoptical correcting unit.
 7. The image pickup apparatus according toclaim 2, wherein a drive mode of the first optical correcting unit is adrive mode for tilting the first optical correcting unit to an opticalaxis of an imaging optical system of the image pickup apparatus, andwherein a drive mode of the second optical correcting unit is a drivemode for shifting the second optical correcting unit in a directionperpendicular to the optical axis.
 8. The image pickup apparatusaccording to claim 2, wherein the first optical correcting unit isarranged closer to an object image in the optical axis directionrelative to the second optical correcting unit.
 9. The image pickupapparatus according to claim 2, wherein resolution for detecting theposition of the first optical correcting unit is less than that of thesecond optical correcting unit.
 10. The image pickup apparatus accordingto claim 2, further comprising: a first feedback controlling unitconfigured to control feedback for a current position of the firstoptical correcting unit; and a second feedback controlling unitconfigured to control feedback for a current position of the secondoptical correcting unit, wherein a frequency band of the second feedbackcontrolling unit is wider than that of the first feedback controllingunit.
 11. An image pickup apparatus comprising: a shake detecting unitconfigured to detect a shake of the image pickup apparatus; a firstoptical correcting unit and a second optical correcting unit configuredto move in a direction different from an optical axis so as to correctoptically an image shake; a first position detecting unit configured todetect a position of the first optical correcting unit and output afirst position detection signal; a second position detecting unitconfigured to detect a position of the second optical correcting unitand output a second position detection signal; and a controlling unitconfigured to control the first optical correcting unit based on a shakesignal output from the shake detecting unit and the first positiondetection signal, and control the second optical correcting unit basedon the shake signal output from the shake detecting unit and the secondposition detection signal, wherein resolution for detecting a positionof the first position detecting unit is different from that of thesecond position detecting unit.
 12. An imaging method, the methodcomprising: detecting a shake of an image pickup apparatus by a shakedetecting unit; moving the image shake in a direction different from anoptical axis so as to correct optically an image shake by a firstoptical correcting unit and a second optical correcting unit; detectinga position of the first optical correcting unit and outputting a firstposition detection signal by a first position detecting unit; detectinga position of the second optical correcting unit and outputting a secondposition detection signal by a second position detecting unit;controlling the first optical correcting unit based on a shake signaloutput from the shake detecting unit and the first position detectionsignal; and controlling the second optical correcting unit based on theshake signal output from the shake detecting unit and the secondposition detection signal, wherein a range for detecting the position ofthe first position detecting unit is different from that of the secondposition detection signal.
 13. An imaging method, the method comprising:detecting a shake of an image pickup apparatus by a shake detectingunit; moving the image shake in a direction different from an opticalaxis so as to correct optically an image shake by a first opticalcorrecting unit and a second optical correcting unit; detecting aposition of the first optical correcting unit and outputting a firstposition detection signal by a first position detecting unit; detectinga position of the second optical correcting unit and outputting a secondposition detection signal by a second position detecting unit;controlling the first optical correcting unit based on a shake signaloutput from the shake detecting unit and the first position detectionsignal; and controlling the second optical correcting unit based on theshake signal output from the shake detecting unit and the secondposition detection signal, wherein resolution for the position detectionof the first position detecting unit is different from that of thesecond position detecting unit.